NATURAL HISTORY. 43 
surface being so very great compared with the 
quantity of matter they contain. 
Otho. Fred. Miller, the Danish naturalist, 
was the first who arranged the infusory animal- 
cules. His classification and descriptions are 
accompanied by drawings of each species, 
which render his work, even at the present day, 
the most valuable we possess, although his 
arrangement has been extended and improved 
by succeeding writers. The basis of his divi- 
sion is, their external characters, and the struc- 
. ture of their envelope. , 
Since the year 1780, the date of Miiller’s 
work, very few facts have been added to this 
part of natural history. The great advance to 
perfection, which the microscope has recently 
“made, and the confidence that, under proper 
management, may be reposed in it, seem to 
warrant the expectation of a great accession to 
our knowledge of these curious animated atoms 
—important from their immense numbers and 
universal occurrence.* 
* Since the above was written, this subject has been exten- 
sively cultivated. See the Author’s last work on this subject, 
entitled A General History of Animaltcules ; illustrated by 500 
engravings. 
